Dresser compensating mechanism for grinding machines



. A. F. MARKUS DRESSER COMPENSATING MECHANISM FOR GRINDING MACHINES Oct.30, 1945.

Filed Aug. 28, 1944 4 Sheets-Sheet l Magus yam 44s 2 dun, m 7% 44 T(fl-rwoxzms J Oct. 30, 1945.

A. F. MARKUS 2,388,067

DRE SSER GOMPENSATING MECHANISM FOR GRINDING MACHINES I 4 Sheets-Sheet 2NvEINTok (AT-r0 Oquyusffl /arkaa MW I S 3 kwmm Q K l i -wHHHHHHM.H..-M-H.wn H u. m. 8 m b Om mm m Q @W y w f mm A. F. MARKUS DRESSERCOMPENSATING MECHANISM FOR GRINDINGMACHINES Filed Aug. 28, 1944 4Sheets$fieet 4 N vbm r'ro p sf f. Wank/s (We! a *Wi W CATTO PatentedOct. 30, 1945 DRESSER COMPEN SATIN G MECHANISM FOR GRINDING MACHIN ESAugust F. Markus, Detroit, Mich., assignor to Ex- Cell-O Corporation,tion of Michigan Detroit, Mich., a corpora- Application August 28, 1944,Serial No. 551,479

10 Claims.

The present invention is intended for application to grinding machinessuch, for example, as thread grinders, and has particular reference togrinding machines incorporating that general class of mechanisms knownas automatic dressing compensators which serve to modify automaticallythe relative displacement of grinding wheel and work by an amountrequisite to compensate for the diminishment in wheel size necessarilyincident to each dressing or truing of the same.

One object of the present invention is to provide a grinding machinearranged to employ movement of a floatingly mounted cylinder foreffecting relative movement between wheel and work supports of themachine and in which a piston within the cylinder is rigid with anon-rotatable nut threaded on a screw so that such screw may be revolvedfor size control purposes andshifted bodily endwise for dressercompensation.

Another object of the present invention is to provide a grinding machineembodying a work support pivoted to be rocked toward and from a grindingwheel by a suitable size control device, together with a novelarrangement for also rocking said work support compensatingly inaccordance with the shift of an independently pivoted dresser supporttoward and from the-wheel.

The invention also resides in various novel relations and combinationsof the parts by means of which effective and reliable operation isaccomplished with a simple, rugged mechanism.

Further objects and advantages of the invention will become apparent asthe following description proceeds, taken in connection with theaccompanying drawings, in which: 7

Figure 1 is a front elevation of a thread grinding machine embodying thepresent invention;

Fig. 2 is a vertical sectional view through the upper portion of themachine and taken substantially along the pivotal axis of the work suppr I Fig. 3 is an end elevation, partially in section along the line 3-3in Fig. 2 of the upper portionoi the machine;

Fig. 3a is a detail sectional view taken substantially along the line3a3a in Fig. 3;

Fig. 4 is a view similar to Fig. 3 but somewhat more diagrammatic incharacter and'showing the dresser support and retract cylinder insection;and

Fig. 5 is a fragmentary detail perspective view of the mount for thewheel support.

While the invention is susceptible of various modifications andalternative constructions, I

have shown in the drawings and will herein de-L scribe in detailthepreferred embodiment, but it is to be understood that I do not therebyintend to limit the invention to the specific form disclosed, but intendto cover all modifications and alternative constructions falling withinthe spirit and scope of the invention as expressed in the appendedclaims.

Referring more particularly to the drawings of the exemplary embodimentof the invention herein disclosed, it will be seen upon reference tothedrawings that the same has been illustrated as embodied in a threadgrinding machine (Fig. 1). Such machine comprises a base ID on the topof which-is a work support, designated generally as II, and includingcenters I2 and I4 between which a work piece (indicated at W in Fig. 2)is received and presented to a rotatively driven grinding wheel I5.Truing of the grinding wheel periphery by some suitable form of dresser,various ones of which are available in the art, is requisite from timeto time as the wheel periphery becomes misshapen by wear. The presentinvention is concerned primarily with an arrangement for automaticallyeffecting a relative relocation of work and wheel upon each dressing ofthe latter in order to compensate for the diminuation in wheel diameternecessarily incident to dressing. Such compensating arrangement is,however, so closely integrated with the related portions of the machinethat a description of the latter, including the work support, wheelsupport, dresser support, etc., is desirable as a preface, even thoughthe details of the same may be widely varied, without departing from thepresent invention.

In the illustrated machine, the work support I I is of the formdisclosed in a grinding machine covered by my copending applicationSerial No. 542,719, filed June 29, 1944. In this exemplary constructionthe work support includes a main frame I6 (Figs. 2 and 3) having anintegral upstanding headstock end plate I? at one end and longitudinallyextending guideways I8 on the opposite end and on which the adjustablyclamped tailstock I9 is received. Such frame It is slidable axiallyalong a pair of aligned guide bars 20, 2I and is adapted to be rocked orpivoted about such bars to carry the work toward and from the grindingwheel I5. The guide bars 20, 2| are fixed in respective pairs ofupstanding lugs 22, 23 and 24, 25 integral with the base I9. Dependingintegral feet 26, 21 on the work support frame I6 are bored to receiverespective ones of the guide bars, the frame being translatable alongsuch bars to shift the work axially, as well as rockable about such barsfor moving the work transaxially with reference to the grinding wheel,

A work supporting spindle 28 (Fig. 2) is journaled in the headstock ofthe work support II by antifriction bearings 29, 30, the latter bearingbeing carried by a tubular extension 3| in a gear housing 32 removablyfixed to the upright plate l 1.: To efiect translation of the worksupport frame H in timed relation with the rotation of the spindle 28,the latter is equipped with a replaceable master lead screw 33 threadedin a non-rotatable nut 34 carried by a supplemental or auxiliary head,designated generally as 35. This auxiliary head is mounted for rockingmotion in unison with the work support frame I6 but is restrainedagainst translation with the latter. Thus the auxiliary head 35 includesa frame 36 having a dependingfoot 31 journaled on a sleeve 38 within thehollow guide bar 2 6 and located at one side of the upstand-' ing lug 22on the base 16. On the opposite side of this lug is a block 39 fixed tothe frame 36 and journaled on the guide bar 20. The frame 36 is thusmounted to pivot about the axis, of the guide bar 26 but is restrainedagainst movement endwise of the latter by the abutment of the foot 31and block 39 with opposite sides of the lug 22. Within the upper portionof the frame 36 is a sleeve 46 journaled for rotative adjustment andhaving the nut 34 removably fixed to its outer end. The tubularextension 31 on the gear case housing 32 is slidably telescoped withinthis sleeve 40 s that the frames [6 and'36 are compelled to pivot inunison about the axis of the guide bars 26, 2!, irrespective of theirrelative axial displacement. Rotational adjustment of the sleeve 46 isaccomplished by a handwheel 4| fixed to a worm'42 meshed with an annulusof worm gear teeth formed at 43 in the periphery of the sleeve, suchrotational adjustment being utilized in determining the lead pick-up. Asheet metal housing 44 encloses the outer end of the auxiliary head 35.

Rotation of the work spindle 28 and its feed screw 33 is accomplishedfrom 'a drive shaft 45- (Fig. 2) disposed concentrically with the axisalso Fig. 1) adjustably clamped to the front face of the work supportframe it rests in sliding engagement with the upwardly projecting noseof a pin 63 carried on the intermediate support 59,

the overhanging weight of the work support retaining contact between thebar and pin at all times. As described in more detail in my copendingapplication, Serial No. 542,719, referred to above, provision may, ifdesired, be made for adjusting the angle of the bar 62 longitudinally ofthe same to impart rocking motion ;to the work support relative to theintermedi- J ate support in timed relation with the translation of theformer for use in grinding tapered shapes, and likewise provision may bemade for automatically raising and lowering the pin 63 through use of aneccentric cam disk 64 driven in timed relation with the rotation of thespindle 28 in accomplishing relief grinding. Such refinements, however,form no part of the present invention and consequently need not beexamined except for the observation that the compensating arrangementhereinafter described does not interfere in any way with their.

function.

Bodily endwise movement of a floatingly mounted cylinder 65 (Figs. 3 and4) is utilized for'rocking the pivoted intermediate support 59,togetherv with the work support carried by the latter.

-Such cylinder constitutes a portion of a rapidretraction mechanism andhas a piston 66 slidable therein, the cylinder itself beingslidablymounted in the present instance within a tubu lar extension 61integral with a bracket 68 fixed to the machine base I0. The cylinder isconnected to a pair of laterally spaced depending feet 69-, integralwith the underside of the intermediate support, by a pair of links!!!(see also of tilting or pivotal motionrof the work support about theguide rods 26, 2| sothat the drive connections will remain undisturbedduring all tilting movement of the latter. This shaft is journaledwithin the tubular sleeve 38 heretofore mentioned and is driven by aworm gear 46 fixed to its outer end and meshed with a worm 4'1. Thelatter worm is, in turn, connected by a pulley 68 and a belt ifl with anelectric drive motor 56 (Fig. 1) fixed to the lower portion of themachine base [6. A pinion 5i fixed to the drive shaft 45 meshes with agear 52 carried by a shaft 53 journaled within the block 39. To completea drive connection for revolving the spindle 28, the shaft 53 has asliding spline connection 54 with a shaft 55 journaled in the main framel6 and carrying a gear 56. The latter meshes with a second gear 51 rigidwith a sleeve 58 keyed to the spindle 23.

Tilting motion is imparted to they work support frame 16 (and to itsconnected auxiliary head 35) through the use of an intermediate supportor apron 59 which underlies the frame l6 (Figs. 2 and 3). Thisintermediate support is pivoted by integral upstanding legs 66, 6| on iton the guide bars 26, 2!, so that it may rock coaxially with the worksupport frame l6 but is restrained against endwise movement with thelatter. A taper control bar 62 (Fig. 3 and see right from the positionshown in Fig. l, thereby rocking the intermediate support and worksupportcounterclockwise to withdraw the work rapidly from the grindingwheel 15. Conversely, ad'- mission of pressure fluid through the port 12and exhausting of fluid from the other port II will thrust the cylinder65 to the left, thereby rocking the work back toward the grinding wheel.

A suitable source'of pressure fluid and control valve (not shown) forsupplying and exhausting pressure fluid to and from the cylinder 65 mayof course be provided. In the present instanceit is intended that thehydraulically effected movement of the cylinder 65 be 'used in effectingrapid retraction of the work at the completion of grindingandrestoration of the work to position for re-institution of grinding.Normally the fluid is locked in the cylinder 65'so that the cylinder iscompelled to move in unison withthe piston whenthe latter moves.

Provision is made herein for moving thepiston 66'axially,'while carryingthe cylinder 65 with it, in order to rock the intermediate and .worksupports both for size control and dresser compensation purposes. Withthat in view the piston 66 is made rigid with a'nut I3 keyed within thecylinder 65 to restrain such nut against rotation and'threaded on ascrew 14. The 'nut 13 and its attached piston 66 may acc OrdingIy,

-Such links are pivoted at their respective opposite ends to such feetand to the cylend through the i p ce axially either by rotating thescrew 14 or shifting the latter bodily in an axial direction. In thepresent machine rotation of the screw is used for size control purposesand bodily endwise movement of the same for dresser compensation.

A sizecontrol mechanism, designated generally as 15, is shown herein asmounted on the base I and arranged to revolve the screw 14, suchmechanism being splined to the screw so that the latter may have freedomof axial movement. In the present instance the size control mechanismincludes a manually rotatable size control wheel 16 for rotating-thescrew. Nor-- nism for automatic power actuation of the screw I4 to turnthe same step-by-step in effecting the desired infeed of the work intimed relation with reciprocation of the work support. I

Turning now to the matter of the mounting of the grinding wheel I5 andits associated dresser mechanism, it will be observed upon reference toFigs. 3 and 4 that the grinding wheel is carried by a wheel supportdesignated generally as T1. Such wheel support includes a centralrectangular plate-like portion 18 having integraltherewith a pair ofupstanding side walls or arms 19 between the upper ends of which thegrinding wheel I5 is journaled. The lower portions of these side wallsare joined by a web 80 integral therewith as well as with the plate I9.Beneath this web is pivotally mounted a bracket 8I carrying a drivemotor82 connected by a belt 83 with the grinding Wheel for revolving thelatter.

The wheel support 11 is mounted on the machine base I0 for adjustmentaxially of the work, as well as for limited angular adjustment inaccommodating respectively positioning of the wheel for operation onvarious longitudinally displaced portions of the work and various helixangles for the threads to be ground on the work. For purposes of suchadjustments, accurately machined fiat surfaces 84, 85 are provided onthe machine base I0 and wheel support 11, respectively, a rectangularblock 85 (see also Fig. 5) being sandwiched between these surfaces. Thisblock presents accurately machined parallel opposite side faces and isreleasably secured to the base I0 by bolts 81 passing through slots 88extending longitudinally of the surface 84, the block "being accuratelyguided for adjustment movement axially of the workpiece by a key 89. Thewheel support 11 is, in turn, similarly secured to the block 86 by boltshaving their heads received in T-slots 90 which are in this instancearcuate. Adjustment movement of the wheel supportwith reference to theblock is accurately The key SI and guided by anarcuate key 9|. slots 90are centered about a line passing through the axes of the work andgrinding wheel. Both lateral and angular adjustment of the grindingwheel l5 can thus be accomplished readily and withprecision. It will beunderstood that the range of angular adjustment need only be quitesmall, that is, of the order of about 5..

A dresser mechanism, designated generally as carried on a dressersupliortig frame 93 pivoted at 94 to the wheel support 11 sothatthedresser mechanism moves bodily with the wheel and wheel supportduring adjustments in position of the latter, thereby obviating anynecessity for relocation of the dresser as an incident to suchadjustments. Th dresser mechanism as such may take a variety of formsand may, for example, be like that disclosed in some detail in GilbertStewart Patent No. 2,311,263, issued February 16, 1943. Inbrief, itcomprises one or more diamond dresser points 95 mounted on the dresserframe 93 for movement with reference to the latter in a predeterminedcycle of movement in which the point or points approach the grindingwheel, engage its periphery to true the same to predetermined contour,and thereafter withdraw out of contact with the wheel back to theirstartingl osition. Movement of the dresser supporting frame 93 thusserve to shift the mean location of the path of movement for the dresserpoints with reference to the grinding wheel and thereby deter mine thedressed diameter of the wheel, the

dresser support being shifted toward the wheel a predetermined incrementas a preliminary to each successive dressing operation.

In the construction shown (Figs. 3 and. 4) the dresser supporting frame93 is of inverted L-shape with depending side walls 96 and is pivotedat94 between the side walls 19 of the wheel support, the pivotal axis ofthe dresser support being parallel with the axis of rotation of thegrinding wheel. 7

A screw 91 (Fig. 4) is used for rocking the dresser supporting frame 93about its pivot 94 toward the grinding wheel I5 transaxially of thelatter. Such screw is threaded in a tubular projection 98 on anupstanding plate 99 integral with the outer end of the web of the wheelsupport 11. A tension spring I00 anchored at its opposite ends to theplate 99 and to the dresser supporting frame 93 retains the latter incontact with the nose of th screw 91. .For manual operation of the screw91 a dresser control wheel MI is fixed to its outer end and may berevolved to advance or retract the dresser supporting frame a desiredamount. In some instances it may be desirable to turnthe screw 91automatically stepby-step in coordination with the cycling of thedresser mechanism. In such case a ratchet wheel I02 is provided which isrigid with the hub of the control wheel IN. A pawl I03 is pivoted on anoscillatable pawl carrier I04 journaled on the cylindrical portion ofthe plate 99 coaxially with the I screw. A guard plate or shield I05overlying a portion of the periphery of the ratchet wheel may be lockedin adjusted position by a thumb nut I06 to overlie a selected portion ofthe teeth other-,- wise exposed to the pawl and thus determine theangular distance through which the ratchet wheel is advanced at eachstroke of the pawl in correspondingly determining the length of eachstepby-stepadvance for the dresser supporting frame 93. plunger I01reciprocable within a bore I08 in the plate 99. Any suitable means maybe provided for actuating this plunger. in timed relation with thecycling of the dresser mechanism 92, the arrangement being in generalsuch that the dresser supporting frame 93 is rocked forward toward thewheel I5 through a predetermined increment of distance preparatory tothe execution by the of movement.

:12 (Figs; stand 4) for the grinding wheel I515" The pawl carrier I05 isoscillated by a suitablefor such timed actuation of the plunger 1 I01.is. disclosed-for example in Ira -J, Snader Patent'No.,2,251-,961,issued August 12,'1941,and ace cordinglyrfurther detailing here isunnecessary.:

In th dresser compensating mechanism here;

in disclosedprovision i made'for shifting'thework support IIcoincidentally with-eachmove'i ment of the dresser-supporting frame 93in1a manner such that the work is repositioned relative tojthe wheel I5by an amount substantially equal, to the diminishmentl in wheel,diameter occasioned by the advanceof the dresserisupporting work support'II througha distance corresponding t each displacementof thedressersupporting frame93. t I

, In the illustrative :construction the linkage 'between the dressersupporting frame 93 and the screw includes a yoke I09 (see Figs, 2and-3) pivoted coaxially with the intermediate support 59 and worksupport I Ion the .guide bar 2 I-. Extending between, the upstandingarmsof this yoke is a rod III! which is slidably pivoted one end ofa link Iextending rearwardly toward the dresser frame and pivoted to the latterat I I2. By. utilizing a sliding connection (including the rod IIII asshown) between the link III and yoke I09, bodily adjustment of the wheeland dresser supports longitudinally, of the work is accommodated withoutinterruption of the linkage connection. For a similar purpose, a balland socket type swivel joint I I I a is interposed in the link IIIintermediate its ends, thus, accommodating the angular adjustment of thewheel support relative to the work.

Depending from the yoke I09 is an integral arm I091; (see Fig. 2) havingpivoted thereto a pair of links I I3 which are pivoted at their forwardends to a collar II4'(see Fig. 4) journaled on the end of-the screw I4and held on the latter to move axially with the same by an abuttingshoulder II5 and'an opposed nut I I6. The pivot points for the pairs'oflinks I0 and I I3 for connectingthe same,

respectively, to the intermediate support 59 and yoke {99 are locatedequidistantly'from the axis of the guide rod 2 I, in order to minimizethe effect of angular displacement between the intermediate support andyoke upon change in wheel diameter. With thedresser supporting frame 93linked to the floating cylinder 65 as described, it will be: seen thatupon each advancev or retreat of the dresser supporting frame the screw14 will be correspondingly displaced axially, thereby carrying with itthe floating cylinder 65 and causing the intermediate and work supportsto be rocked through a commensurate distance.

In theoperationof thegrinding machinedisclosed, the operator may turnthedresser control wheel IIlI until the dresser supporting frame 93isrocked forward a'sufiicientdistance for effective engagement of thedresserpoint or points with the grinding wheele Then thedresser-mechanism may be cycled to dress thewheel periphery to a desiredshape for the grinding operation to follow. Pressure fluid is'admittedthrough the righthand port II of the cylinder 65 to thrust the pistonfBS to the left and thus rock the intermediate and'worksu'pp'orts 59,II clockwise for rapid approach of the work into adjacency with thegrinding wheel. ,The'motor' 59 revolves and traverses thlwork in timedrelation through the drive connections heretofore described and the sizecontrol mechanism-I5 is'utilized to rock thework. step-by-steptransaxially toward the wheel intimed relation. with the reciprocationsof the,

work, all in the usual manner, until a thread of desired depth has beenground in the work. At such times as may be required, the cylinder 65 isshifted relative to the piston 66 to withdraw the work from the wheeland the dresser mechanism 92 is caused to execute a cycle of movementfor dressing the wheel. Preparatory to each such cycling of thedressermechanism, the screw 9! is revolved a predetermined distance torock the, dresser supporting frame forward fora desired increment ofdresser feed. As the dresser supporting frame 93 swings-forward thelink. III" thruststhe yoke I09 clockwise about its pivotal axis. Suchmovement of the yoke in turn thrusts the screw I4 axially to'the left,the latter carrying the piston and cylinder 66, B5 with'it. Accordingly,the intermediate and. work supports are rocked clockwise to advance thework relative to i the wheel, the geometry of the parts being such thatthe advance of the work thus effected is sub 1 stantially preciselyequal to the diminishment of g wheelsize which will result from thecoincidentadvance-of the dresser supporting frame 93.

I'claim as my invention: 1. In a grinding machine, the combination ofrelatively movable work and wheel supports, said wheel support carryinga rotatively driven grinding wheel, a rotatable screw having a nutthreaded thereon with the latter restrained;

against rotation, a fluid operated piston rigid with said nut andslidable endwise within a floatingly. mounted cylinder, the admission ofpressurefluid to alternate ends of said cylinder servingto displace saidcylinder endwise of said screw and travel of said nut axially of saidscrew as an incident to rotation of the latter serving to carry saidcylinder in a direction endwise of said screw, size; control means forrevolving said screw, and means mechanically connecting said cylinder toone of said supports for moving the latter rela tive to the othersupport in accordancewith 2. In a grinding machine, the combination of abase, work and wheel supports, the latter having a rotatively drivengrinding wheel thereon,

means -pivotally mounting said worksupport on said base for rocking ofthe same toward and from said wheel generally transaxially of thelatter,. size control mean for rocking said work support, a dressersupport pivoted on said wheel support. to rock, toward and from saidwheel, means onerable in accordance with changes in position of saiddresser support with reference to said wheel support for correspondinglyrocking said work.- support, and means for effecting bodily adjustment.as aunit of said wheel supportandethe dresser support pivoted thereonto vary the angle of said wheel with reference to a work piece carriedby said work support.

supports mounted thereon, the latter carrying a rotatively drivengrinding wheel, a rotatable screw having a nut threaded thereon with thenut restrained against rotation, size control means for revolving saidscrew to cause said nut to travel axially therealong, connecting meansfor connecting said nutto one of said supports for moving the latterrelative to the other support upon endwisedisplacernent of said nut,said connecting means including a fluid operated piston and cylinder formoving said one support relative to the other support between twoalternatively available limit positions independently of movement ofsaid nut, a dresser support movable toward and from said wheel, andmeans for displacing said screw endwise in accordance with changes inposition of said dresser support to thereby shift said nut and theconnected one of said first-mentioned supports accordingly.

5. In a grinding machine, the combination of a base having a wheelsupport thereon carrying a rotatively driven grinding wheel, a worksupport pivoted on said base for rocking motion generally transaxiallyof said wheel, a rotatable screw having a nut threaded thereon with thenut restrained against rotation, size control means for revolving saidscrew to cause said nut to travel axially therealong, connecting meansfor connecting said nut to said work support for rocking the lattertoward and from said wheel in accordance with endwise displacement ofsaid nut, said connecting means including a fluid operated piston andcylinder for moving said work support toward and from said Wheel betweentwo limit positions independently of any movement of said nut, a dressersupport movable toward and from said wheel, and means for displacingsaid screw endwise in accordance with changes in position of saiddresser support to thereby shift said nut and the connected work supportaccordingly.

6. In a grinding machine, the combination of relatively movable work andwheel supports, said wheel support carrying a rotatively driven grindingwheel, a rotatable screw having a nut threaded thereon with the latterrestrained against rotation, a fluid operated piston rigid with said nutand slidable endwise within a floatingly mounted cylinder, the admissionof pressure fluid to alternate ends of said cylinder serving to displacesaid cylinder endwise of said screw and travel of said nut axially ofsaid screw as an incident to rotation of the latter serving to carrysaid cylinder in a direction endwise of said screw, size control meansfor revolving said screw, means mechanically connecting said cylinder toone of said supports for moving the latter relative to the other supportin accordance with movement of said cyl inder in a direction endwise ofsaid screw, a dresser support adjustable toward and from said wheel, andmeans mechanically connecting said screw to said dresser for endwisedisplacement of said screw in accordance with adjustment in dressersupport position and to restrain said screw against endwise displacementwhen said dresser support is at rest.

7. In a grinding machine, the combination of a base having a wheelsupport thereon carrying a rotatively driven grinding wheel, a worksupport pivoted on said base for rocking motion generally transaxial ofsaid wheel, a rotatable screw having against rotation, a fluid operatedpiston rigid with said nut, and slidable endwise, within a cylinderfloatingly mounted on said base, admission of pressure fluid toalternate ends of said cylinder serving to displace the latter endwiseof said screw and travel of said nut axially of said screw as anincident to rotation of the latter serving to carry said cylinder in adirection endwise of said screw, size control means for revolving saidscrew, and a linkage connecting said cylinder to said work support forrocking of the latter toward and from said wheel in accordance withmovement of said cylinder in a direction endwise of said screw.

8. In a grinding machine, the combination of a base "having a wheelsupport thereon carrying a rotatively drivengrindin'g wheel, a worksupport pivoted on said base for rocking-motion generally transaxialofsaid wheel, a rotatable screw having a'nut threaded thereon with the nutrcstrained against-rotation, a fluid operatedp iston rigid with said nutand slidable endwise within a cylinder floatingly mounted on said base,admission of pressure fluid to alternate ends of said cylinders servingto displace the latter endwise of said screw and travel of said nutaxially of said screw as an incident to rotation of the latter servingto carry said cylinder in a direction endwise of said screw, sizecontrol means for revolving said screw, a linkage connecting saidcylinder to said work support for rocking of the latter toward and fromsaid wheel in accordance with movement of said cylinder in a directionendwise of said screw, a dresser support adjustable toward and from saidwheel, and means mechanically connecting said screw to said'dressersupport for endwise displacement of said screw in accordance withadjustment in dresser support position and to restrain said screwagainst endwise displacement when said dresser support is at rest.

9. In a grinding machine, the combination of a base having a wheelsupport thereon carrying a rotatively driven grinding wheel, a worksupport disposed at one side of said grinding wheel, means mounting saidwork support on said base for rocking of said work support generallytransaxially of said wheel and for translation of said Work support in apath generally paralleling the wheel axis, an intermediate supportunderlying said work support with the latter resting on the same, meansmounting said intermediate support on said base for movement about apivotal axis coincident with the pivotal axis of said work support butwith the intermediate support restrained against translation, a screwextending transversely beneath said intermediate support and having anut threaded thereon with the nut restrained against rotation, a fluidoperated piston rigid with said nut and slidable endwise within afioatingly mounted cylinder, the admission of pressure fluid toalternate ends of said cylinder serving to displace the latter endwiseof said screw, and travel of said nut axially of said screw as anincident to rotation of the latter serving to carry said cylinder in adirection endwise of said screw, size control means for revolving saidscrew, said intermediate support having a depending leg thereon, linkagepivotally connecting said leg to said cylinder for rocking of saidintermediate support about its pivot in accordance with endwise movementof said cylinder, a dresser support adjustable toward and from saidwheel, and a second linkage connecting said dresser support to saidscrew for bodily endwise displacement of the latter in aca nut threadedthereon with the nut restrained 6 coma nee with changes in position ofsaid dresser support.

10, In a grinding machine, the combination of a base having awheelsupport thereon carrying a rotatively driven grinding wheel, aworksupport disposed at one side of said grinding wheel, means mountingsaid work support on said base for rocking of said work supportgenerally transaxially of said wheel and for translation of said worksupport in a path generally paralleling the wheel axis, an intermediatesupport underlying said I work support with the latter resting on thesame,

means mounting said intermediate support on said .hasefor movement abouta pivotal axis coincident withthe pivotal axis of said work support butwith the intermediate support restrained against translation, a screwextending transversely bei neath said intermediate support and having anut threaded thereon with the nut restrained against rotation, a fluidoperated piston rigid with said nut and slidable endwise within afioatingly mounted cylinder, the admission of pressure fluid toalternate ends or said cylinder serving to displace the latter endwiseof said screw, and travel of said nut axially of said screw 'as'anincident to rotation of the latter serving to carry said cylin- -rder ina direction endwise of said screw, size control means for revolving saidscrew, said interme- -diate support having a depending leg thereon,linkage pivotally connecting saidleg to saidcylinder for rocking of saidintermediate support about its pivot in accordance withendwisefin'ovement of said cylinder, a dresser'support adjustable towardand from said wheel,'a second depending leg of a length equal to thefirst-mentioned one and pivoted to swing on an axis coincident'with thecommon pivotal axis of said intermediate and work supports, and linkagemeans interconnecting said dresser support and said screw through saidsecond leg for bodily displacement of said screw in an endwise directionin accordance with changes in position of said dresser support.

AUGUST F. MARKUS.

